iOpenShell » Q-Chem specific questions » EOM-CCSD calc memory options

EOM-CCSD calc memory options

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Author Post
Member
Registered: Oct 2012
Posts: 16
Hello all,

I'm trying to run an EOM-CCSD calculation, but I'm running into the following error at the beginning of the CCMAN2 program.


In TrnAlg: available memory = 84080238
needed mmory = 355107312
Q-Chem fatal error occurred in module 0, line 283, PE 0:
Insufficient memory for semidirect MP2


Assuming these are in words, it's a pretty small amount (0.7 and 3 gb respectively) given I'm running it on a single node that has ~240 gb of free ram.
My questions is, which memory option should change the amount of "available memory"?
I've toyed with mem_static (up to 4000), mem_total and cc_memory (from 10,000 to 200,000) - but they all return the same error with the same amount of available memory. Am I missing a memory keyword?

The calculation is on tetracene, C18H12, with a cc-pvtz basis (708 basis fxns). I'm aware this is a large (maybe too large) system.
But I was hoping with symmetry that it would be feasible on our high-mem node. I'm running Qchem 4.3

Any suggestions welcome
~AC
Member
Registered: Oct 2012
Posts: 16
So, I'm able to workaround this memory issue using RI-EOM-CCSD and the rimp2-cc-pvtz auxiliary basis.

The original issue is still unresolved, and I wouldn't mind some insight into ccman2's memory management,
but it is no longer a pressing issue.

Thanks for considering my problem,
Alan Chien
Administrator
Registered: Sep 2007
Posts: 175
The crash is indeed due to insufficient mem_static in old integral transformation. The max size for mem_static is 2 GB, so if it is too small for your job, this is it. Luckily, we now have a new integral library and integral transformation, which does not need mem_static and is more efficient and parallel. It is default in the current qchem. Try libqints = true with your version -- I do not remember whether it was enabled in 4.3 If it does not work -- update.
Member
Registered: Oct 2012
Posts: 16
Ah, that is great to hear, thanks very much!

~AC

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